spm App target builds and links!

Plugins/CargoPlugin/Plugin.swift

@@ -54,7 +54,7 @@ struct CargoPlugin: BuildToolPlugin {
 #if canImport(XcodeProjectPlugin)
 import XcodeProjectPlugin
 
-extension SwiftLintPlugin: XcodeBuildToolPlugin {
+extension CargoPlugin: XcodeBuildToolPlugin {
 	func createBuildCommands(context: XcodePluginContext, target: XcodeTarget) throws -> [Command] {
 		let inputFilePaths = target.inputFiles
 			.filter { $0.type == .source && $0.path.extension == "swift" }
@@ -68,3 +68,43 @@ extension SwiftLintPlugin: XcodeBuildToolPlugin {
 	}
 }
 #endif
+
+#if os(Linux)
+import Glibc
+#else
+import Darwin
+#endif
+
+extension Path {
+	/// Scans the receiver, then all of its parents looking for a configuration file with the name ".swiftlint.yml".
+	///
+	/// - returns: Path to the configuration file, or nil if one cannot be found.
+	func firstConfigurationFileInParentDirectories() -> Path? {
+		let defaultConfigurationFileName = ".swiftlint.yml"
+		let proposedDirectory = sequence(
+			first: self,
+			next: { path in
+				guard path.stem.count > 1 else {
+					// Check we're not at the root of this filesystem, as `removingLastComponent()`
+					// will continually return the root from itself.
+					return nil
+				}
+
+				return path.removingLastComponent()
+			}
+		).first { path in
+			let potentialConfigurationFile = path.appending(subpath: defaultConfigurationFileName)
+			return potentialConfigurationFile.isAccessible()
+		}
+		return proposedDirectory?.appending(subpath: defaultConfigurationFileName)
+	}
+
+	/// Safe way to check if the file is accessible from within the current process sandbox.
+	private func isAccessible() -> Bool {
+		let result = string.withCString { pointer in
+			access(pointer, R_OK)
+		}
+
+		return result == 0
+	}
+}